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Windows 10 1507Operating system · Microsoft

CVE-2025-59259

MEDIUM · 6.5 CVSS v3.1 Published 2025-10-14
Fix available
A fix is available. Upgrade to 10.0.10240.21161 / 10.0.14393.8519 or later.
See remediation →
71/100
Remediation priority · Elevated
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Improper validation of specified type of input in Windows Local Session Manager (LSM) allows an authorized attacker to deny service over a network.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

Windows Local Session Manager (LSM) has improper validation of a specified type of input, allowing an authorized attacker to cause a denial of service condition over a network. The vulnerability stems from insufficient input validation in the LSM component, which processes session management requests.

MitigationApply the Microsoft security update for CVE-2025-59259 when released. Until the patch is available, consider network segmentation and restricting access to LSM functionality to authorized personnel only to reduce the attack surface.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Windows 10 1507Operating system
Affected:< 10.0.10240.21161
Windows 10 1607Operating system
Affected:< 10.0.14393.8519
Windows 10 1809Operating system
Affected:< 10.0.17763.7919
Windows 10 21h2Operating system
Affected:< 10.0.19044.6456
Windows 10 22h2Operating system
Affected:< 10.0.19045.6456
Windows 11 22h2Operating system
Affected:< 10.0.22621.6060
Windows 11 23h2Operating system
Affected:<= 10.0.22631.6060
Windows 11 24h2Operating system
Affected:< 10.0.26100.6899

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check Windows build version
    Open Command Prompt or PowerShell and run 'winver' or 'systeminfo | findstr /B /C:"OS Version"' to obtain the full build number including the KB suffix
    Affected if The build number is less than the threshold for your Windows version (e.g., < 10.0.10240.21161 for Win10 1507, < 10.0.14393.8519 for Win10 1607, etc.)
  2. Identify Windows edition and build
    Run 'systeminfo' and note the OS Name, OS Version, and Build number. Match your version to the affected product list (Windows 10 1507, 1607, 1809, 21h2, 22h2, or Windows 11 22h2, 23h2, 24h2)
    Affected if Your specific Windows edition and build combination falls below the version thresholds listed in the affected products
  3. Verify LSM service status
    Open Services (services.msc) and locate the 'Local Session Manager' service, or run 'sc query LSM' in Command Prompt to check if the service exists and its state
    Affected if The LSM service is running and exposed to network requests (the vulnerability allows network-based denial of service)

You are affected if your Windows build number is lower than the threshold for your specific Windows version and the LSM service is accessible over the network.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 10.0.10240.21161 / 10.0.14393.8519 / 10.0.17763.7919 or later
Fixed in 10.0.10240.2116110.0.14393.851910.0.17763.7919
Interim mitigation

Apply the Microsoft security update for CVE-2025-59259 when released. Until the patch is available, consider network segmentation and restricting access to LSM functionality to authorized personnel only to reduce the attack surface.

Recommended fix High confidence

Apply Microsoft Security Update KB5055528 (or subsequent relevant security update) - the fixed builds are: Windows 10 1507 (10.0.10240.21161+), Windows 10 1607 (10.0.14393.8519+), Windows 10 1809 (10.0.17763.7919+), Windows 10 21h2 (10.0.19044.6456+), Windows 10 22h2 (10.0.19045.6456+), Windows 11 2

  1. Open Windows Settings by pressing Win+I
  2. Navigate to Update & Security > Windows Update
  3. Click 'Check for updates' to download and install available security updates
  4. If the specific KB update for CVE-2025-59259 is listed, ensure it is selected for installation
  5. Restart the system after updates are installed to complete the remediation
  6. Verify the installed updates by checking the update history or running 'winver' to confirm the build number matches or exceeds the fixed version for your Windows release
Caveat Standard Windows update risks - ensure critical workloads are backed up before applying updates in production environments

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Windows 10 1507 Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,560.

Scan for this in your stack

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dbcve dependency scanner

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-59259 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data